Air cooled horticulture lighting fixture for a double ended high pressure sodium lamp

ABSTRACT

An air cooled double ended high pressure sodium lamp fixture for growing plants in confined indoor spaces. The fixture seals the lamp and heat generated by the same to a reflector interior. Flow disruptors create turbulence in a cooling chamber thereby enhancing thermal transfer into a cooling air stream that flows over and around the reflector&#39;s exterior side thereby convectively cooling the lamp using the reflector as a heat sink. The lamp is effectively maintained at operational temperatures and the fixture housing is insulated from the hotter reflector by a gap of moving cooling air, allowing use of the double ended HPS lamp in confined indoor growing spaces.

RELATED APPLICATIONS

N/A

BACKGROUND OF THE INVENTION

1. Technical Field of the Invention

This invention relates generally to horticulture light fixtures forgrowing plants indoors, and particularly to an air cooled fixture usedin confined indoor growing spaces that burns a double ended highpressure sodium lamp.

2. Description of Related and Prior Art

Horticulture light fixtures used for growing plants in confined indoorspaces must provide adequate light to grow plants, while not excessivelyraising the temperature of the growing environment. Removal of the heatgenerated by the fixture is commonly achieved by forcing cooling airaround the lamp and through the fixture, exhausting the same out of thegrowing environment. The air used for cooling the fixture is not mixedwith the growing atmosphere, as the growing atmosphere is speciallycontrolled and often enhanced with Carbon Dioxide to aid in plantdevelopment and health.

Innovations in electronic ballast technology made feasible for use inthe indoor garden industry an improved high pressure sodium ‘HPS’ growlamp that is connected to power at each end of the lamp, thus the term“Double Ended”. The double ended lamp as powered from each end is alsosupported by sockets at each end, thereby eliminating the need for aframe support wire inside the lamp as required in standard single endedHPS lamps. The absence of frame wire eliminates shadows that commonlyplague single ended HPS lamps. The double ended lamp further benefitsfrom a smaller arc tube that is gas filled rather than vacuumencapsulated. The smaller arc tube equates to a smaller point source oflight, thereby improving light projection control and photometricperformance. The double ended HPS lamp proves to be more efficient thanits single ended HPS lamp equivalent, last longer than like wattage HPSlamps, and produces more light in beneficial wavelength for growingplants than any single ended HPS lamps of the same light output rating.

The double ended HPS lamp, with all of its light output performanceadvantages, has a significant particularity in operation, specificallywhen cooling the lamp. Operating temperatures at the lamp envelopesurface must be maintained within a narrow operating range else thedouble ended HPS lamp's efficiencies in electrical power conversion intolight energy are significantly reduced. When impacted by moving air, thedouble ended HPS lamp draws excessive electrical current which may causefailure or shutdown of the ballast powering the lamp. When bounded bystagnant air held at constant operating temperature the double ended HPSlamp proves more efficient in converting electricity to light energy andproduces more light in the plant usable spectrum. This particularity inthe double ended HPS lamp makes it an excellent grow lamp, but alsothwarted earlier attempts to enclose, seal, and air cool the doubleended HPS lamp to be used in confined indoor growing application due tothe lamp's substantial sensitivity to moving cooling air.

Another challenges not resolved by the prior art involves sealing theglass sheet to the bottom of the fixture. The reflector interiortemperatures when burning a double ended HPS lamp cause failures ofgasket materials. Further, the ultraviolet and infrared light energiesproduced by the double ended HPS lamp degrade and make brittle rubber,neoprene, and most other gasket materials suitable for sealing the glasssheet.

Gavita, a lighting company from Holland produces various fixturesutilizing the double ended HPS lamp. The usual configuration includes areflector with a spine, the spine having a socket on each opposing endsuch that the double ended lamp is suspended under a reflector over theplants. The reflector is not sealed from the growing environment, nor isthere a housing enclosure or ducts to facilitate forced air cooling. TheGavita fixtures provide the benefit of the high performing double endedHPS lamp, but lacks air cooling capability which is necessary in manyindoor growing applications as discussed above.

Based on the foregoing, it is respectfully submitted that the prior artdoes not teach nor suggest an air cooled horticulture fixture for adouble ended HPS lamp suitable for growing plants in confined indoorgrowing spaces.

SUMMARY OF THE INVENTION

In view of the foregoing, one object of the present invention is toprovide an air cooled double ended HPS lamp fixture for growing plantsin confined indoor environments.

A further object of this invention is to provide a fixture constructwherein the excessive heat generated by the lamp is removed using astream of forced air.

It is another object of the present invention to provide a stagnant airspace around the lamp that is maintained at constant temperatures withinthe reflector during operation to prevent the lamp from drawingexcessive current when subjected to temperatures differentials, ordirect moving cooling air

Another object of the present invention is to provide a positive airtight seal between the fixture and the growing environment using agasket that is protected from the lamp's damaging light.

This invention further features turbulence enhancement of the coolingair stream by a diverter that disrupts the air stream creating eddiesover the top of the reflector.

Other objects, advantages, and features of this invention will becomeapparent from the following detailed description of the invention whencontemplated with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Elements in the figures have not necessarily been drawn to scale inorder to enhance their clarity and improve understanding of thesevarious elements and embodiments of the invention. Furthermore, elementsthat are known to be common and well understood to those in the industrysuch as electrical power connection are not necessarily depicted inorder to provide a clear view of the various embodiments of theinvention, thus the drawings are generalized in form in the interest ofclarity and conciseness.

FIG. 1 shows an isometric exploded view of the preferred embodiment ofthe inventive fixture;

FIG. 2 is a cutaway exploded side view of the fixture in FIG. 1;

FIG. 3 is a diagrammatically section end view of the fixture in FIG. 1;

FIG. 3A is a perspective exploded view of the flow disruptor in FIG. 1;

FIG. 3B is a perspective exploded view of the flow disruptor in FIG. 3Afurther including turbulators;

FIG. 4 is a cutaway corner of the fixture in FIG. 1 showing thecompressively deformed shadowed gasket;

DETAILED DESCRIPTION OF THE DRAWINGS

As depicted and shown in the FIGs, a “heat sink” is a component used forabsorbing, transferring, or dissipating heat from a system. Here, thereflector 100 acts as the “heat sink” for the lamp 2 which is isolatedfrom the cooling air stream 310 within the reflector interior side 101.The reflector 100 convectively transfers heat generated by the lamp 2into the cooling air stream 310. “Convectively transfers” refers to thetransport of heat by a moving fluid which is in contact with a heatedcomponent. Here, the fluid is air, specifically the cooling air stream310 and the heated component is the reflector 100. Due to the specialprerequisite criteria that the double ended high pressure sodium (HPS)lamp 2 be isolated from moving air, and specifically the cooling airstream 310, the heat transfer is performed convectively from thereflector exterior side 102 to the cooling air stream 310. The rate atwhich the heat transfer can convectively occur depends on the capacityof the replenish able fluid (i.e. cooling air stream 310) to absorb theheat energy via intimate contact with the relatively high temperature atthe reflector exterior surface 102. This relationship is expressed bythe equation q=hAΔT, wherein, “h” is the fluid convection coefficientthat is derived from the fluid's variables including composition,temperature, velocity and turbulence. “Turbulence” referring to achaotic flow regime wherein the fluid/air undergoes irregular changes inmagnitude and direction, swirling and flowing in eddies. “Laminar” flowreferring to a smooth streamlined flow or regular parallel patterns,generally having a boundary layer of air against the surface over whichthe laminar flow moves. When cooling with a heat sink device within acooling medium such as air, turbulent flow proves more effective intransferring heat energy from the heat sink into the flowing air.Turbulent flow acts to scrub away the boundary layer or push away thestagnant layer of air that is closest to the heat sink, therebyenhancing the fluid convection coefficient increasing heat transfer.Turbulent flow also increases velocities and pressures on the surface tobe cooled, increasing thermal transfer. The term “Turbulator” asreferenced herein is a device that enhances disruption of a laminar flowinto a more turbulent flow.

Referring now to FIG. 1-2, the preferred embodiment of the fixturecomprises a reflector 100 captured within a housing 200 defining acooling chamber 300 within the air space located between the reflectorexterior side 102 and housing interior 220, the cooling chamber 300being in air communication with a first duct and second duct. A coolingair stream 310 is disposed through the cooling chamber 300 between thefirst duct 235 and the second duct 245. Two lamp sockets 230A-B locatedpartially through two opposing reflector apertures 105A-B provide theinstall location for the double ended HPS lamp within the reflectorinterior side 101. A flow disruptor 160 fixates over each socket 230A-Band aperture 105A-B diverting moving air from entering the reflectorinterior side 101 while further creating air eddies and local airturbulence within the cooling chamber 300 between the sockets over thereflector top 104 at the reflector's 100 hottest spot, substantiallyabove the lamp 2. The flow disruptor 160 interference with the coolingair stream 310 creates air eddies, increases local vortex velocitieswithin the cooling chamber 300, scrubs away boundary layers of airproximal to the reflector exterior side 102 that reduce heat transfer,thereby enhancing convective heat transfer from the reflector 100 intothe cooling air stream 310.

With reference to FIG. 1 and FIG. 2, the fixture 1 includes a housing200, a reflector 100 captured within the housing 200, a cooling chamber300 defined by the air space between the housing 200 interior and thereflector exterior side 102. The cooling chamber 300 being in aircommunication with a first duct 235 and second duct 245, locatedsubstantially on opposite sides of the housing 200. Between the firstduct 235 and the second duct 245 flows the cooling air stream 310through the cooling chamber 300, the cooling air stream 310 which ispushed or pulled by remote fan not shown but commonly used in the priorart, connected by hose or ducting to the first duct 235.

Before flowing over the reflector top 104, the cooling air stream 310 issplit or deflected by the flow disruptor 160 enhancing turbulent flowthereby increasing thermal transfer from the reflector interior side101, through the reflector 100, convectively transferring from thereflector exterior side 102 into the cooling air stream 310. The hottestarea of the reflector 100 is the reflector top 104 directly above thelamp 2, which is the closest structure to the light source. As capturedwithin the housing 200, the reflector 100 has a reflector top air gap104A defined between the reflector top 104 and the housing interior 220.The reflector top 104 air gap 104A for the preferred embodiment using a1000 watt double ended HPS lamp is ⅜ of an inch, which provides amplecooling chamber 300 space for turbulent air movement as between thereflector top 104 and the housing interior 220 facilitating adequatecooling while maintaining an acceptably air insulated housing 200exterior temperature.

By cutaway illustration with dashed lines in FIG. 2, the lamp 2 is showninstalled by its ends into the sockets 230A-B within the reflectorinterior side 101 near the reflector top 104. The lamp 2 is shownoriented parallel to the cooling air stream 310, however, the robustdesign allows for the lamp 2 to be oriented within the reflector 100 atany diverging angle relative to the cooling air stream 310.

As shown diagrammatically by sectioned view in FIG. 3, cooling airdirections being depicted by arrows illustrates the cooling air stream310 as impacted by the flow disruptor 160. In operation, the cooling airstream 310 is being forced to move with a fan (not shown) either by fanpush or fan pull through the first duct 235, then into and through thecooling chamber 300 to be exhausted out the second duct 245. The coolingair stream 310 is diverted and split by a flow disruptor 160 directingpart of the air over one side of the reflector exterior 102, the otherpart over the other side of the reflector exterior 102. The divertedcooling air stream 310 is redirected within the fixture 1 such thatmoving air is discouraged from pressuring any apertures, gaps, orthrough holes in the reflector 100.

As depicted in FIG. 3 and shown in FIG. 3A, the flow disruptor 160constructed to be deflecting and disrupting to moving air and arrangedto attach over at least one socket 230 and enclose at least one aperture105 such that cooling air moving through the cooling chamber 300 isdiverted and disrupted into a more turbulent flow than a laminar flowregime. The preferred embodiment locates the flow disruptor 160 toencourage deflection of moving air away from the sockets 230 andaperture 105 as discussed above, essentially fulfilling two functions,creating turbulence within the cooling chamber 300 while alsoredirecting moving air away from reflector areas 100 that may be subjectto leaks. The flow disruptor 160 location is not limited to enclosingthe sockets 230 or apertures 105, as a flow disruptor 160 located withinthe first duct 235 or second annular duct 245, depending on whichreceives the incoming cooling air stream 310, is effective atintroducing turbulence into the cooling air stream 310, and depending onwhich configuration may be preferred. Additional flow disruptors 160working independently or in cooperation may be included within thecooling chamber 300 mounted to the reflector 100 or the housing 200.

The preferred embodiment design of the flow disruptor 160 shown in FIG.3A is simply constructed from a first sheet metal portion 160A and asecond sheet metal portion 160B, the preferred metal being steel overaluminum, as the thermal conductivity of the flow disruptor 160 is notas important as the costs associated with manufacture, but in practiceboth metals are suitable. As shown in FIG. 3A, the flow disruptor 160 isimpervious to moving air to facilitate the dual function of deflectingmoving air away from the reflector apertures 105 while also creatingturbulence within the cooling chamber 300.

As shown in FIG. 1B, an enhanced flow disruptor 160 having turbulators161 illustratively depicted as rows of through holes. The turbulators161 could also be fins, blades, vents, or grating, most any disruptingstructure, redirecting channel, or obstacle for the cooling air stream310 will cause turbulence and thereby increase thermal conductivity fromthe reflector 100 into the cooling air stream 310.

As discussed above, the reflector 100 is a thermally conductivecomponent of the fixture acting as a heat sink for the lamp 2. Thereflector 100 preferably is constructed from aluminum, which is thefavored material because of its relatively high thermal conductivity,easily shaped and formed, and highly reflective when polished. The highthermal conductivity of aluminum provides beneficial heat transferbetween the reflector interior side 101 to the reflector exterior side102 thermally transferring or heat sinking through the reflector 100.Steel is also a suitable material, however the lower thermalconductivity makes aluminum the preferred reflector 100 material.

As shown in the FIGs, openings, gaps, or spaces through the reflector100 are filled, blocked, or covered such that the reflector interiorside 101 is sealed from moving air. As assembled and captured within thehousing 200, a first socket 230A is disposed to fill a reflector 100first aperture 105A sealing the first aperture 105A from moving air. Asecond socket 230B is disposed to fill the second aperture 105B sealingthe second aperture 105B against moving air. The first socket 230A andsecond socket 230B constructed and arranged to cooperatively receive theends of the double ended HPS lamp 2 as located within the reflectorinterior side 101 between the two sockets 230A-B. As shown from the sidein FIG. 2 and by depiction in FIG. 3, flow disruptors 160 attach overthe sockets 230A-B and over both apertures 105A-B within the path of thecooling air stream 310. In this way, the flow disruptors 160 enclose anyopening or space between either socket 230A-B and aperture 105A-Brespectively, thereby diverting air moving through the cooling chamber300 away from any potential opening into the reflector interior side101. Filling of each aperture 105A-B by partial insert of each socket230A-B requires precise manufacturing tolerances or specially formedsockets 230 in order to prevent or substantially stop moving air fromtraveling around the socket 230 into the reflector interior side 101.Heat resistant sealing mediums like metal tape or high temp calk areavailable to positively seal the aperture 105 to the socket 230 therebydiverting the cooling air path 310 from entering the reflector interiorside 101. However, high temperature sealing mediums tend to beexpensive, and application of the sealing medium as performed manuallyis often messy, slow, and leaves one more step in the manufacturingprocess subject to human error. As discussed herein, the preferredembodiment utilizes flow disruptors 160 constructed from sheet metalthat are impervious to air rather than sealing mediums. However sealingmediums if properly applied will work in the place of a flow disruptor160 for the limited purpose of sealing the reflector interior 101, butlack the aerodynamic structure necessary to disturb the cooling airstream 310 creating turbulence between the first socket 230A and secondsocket 230B for enhanced convective transfer of heat from the reflector100 into the cooling air stream 310.

In FIG. 4 a sectional view with a close up of the bottom corner of thefixture 1 showing by illustration the cooling chamber 300 as definedbetween the reflector 100 and the housing 200. The cooling chamber 300is shown in cross section demonstrating from top to bottom the relativesize of air space between the reflector 100 and the housing 200 for thepreferred embodiment. As shown, there is only one continuous coolingchamber 300, however several smaller cooling chambers 300 split bydisruptors 160 or mounting fins between the housing interior 220 and thereflector 100 provide greater control of the movement of the cooling airstream 310 through the fixture 1.

The lower left close up view shown in FIG. 4 of the bottom corner of thefixture 1 demonstrates the lower lip 103 of the reflector 100 locationas captured within the housing 200, wherein the lower lip 103 isadjacent to and slightly extending below the housing lower edge 210. Ascaptured, the reflector's 100 lower lip 103 and housing lower edge 210thermally transfer heat energy. This heat sinking occurring between thereflector's 100 hotter lower lip 103 and the housing 200 cooler loweredge 210 makes the lower lip 103 the coolest part of the reflector 100,making for the most suitable place to seal the reflector 100 using agasket 31. A specially formed reflector lip 103 protectively shadows thegasket 31 from damaging light energy produced by the double ended HPSlamp 2 thereby preventing premature failure of the gasket 31 duringoperation. As compressed, the gasket seals against the housing edgesurface slightly deforming 31A to further seal against the reflector lip103. In this way, a double redundant seal is provided between thefixture interior and the growing environment, while also providing apositive air tight seal between the cooling chamber 300 and thereflector interior side 101 that is not as susceptible to premature sealfailure.

As shown in FIG. 4, the compressive sealing between the glass sheet 30and the housing edge 210 with a gasket 31 sandwiched in between therebyseals the growing environment from the fixture interior. The gasket 31being located relative to the reflector 100 such that the reflectorlower lip 103 shadows or blocks direct light 2A produced by the lampfrom impacting the gasket 31. As shown, the glass sheet 30 is held inplace compressively by at least one latch 32 with enough compressiveforce to deform the gasket 31. The deformed gasket 31A sealinglycontacts the lower lip 103 making a second redundant seal against thecoolest part of the reflector 100 at the lower lip 103 which is shadowedand protected from the direct light energy produced by the lamp 2. Forthe preferred embodiment the gasket 31 is constructed of a porousneoprene material, however many suitable heat resistant gasket materialsmay be used to construct the gasket 31.

The inventive fixture as shown may have the cooling air pushed or pulledthrough the cooling chamber 300 by fan or other forced air apparatus.The robust fixture 1 cools effectively with either a negative pressureor positive pressure within the housing 200 due to the isolatedreflector 100 interior side 101. Two fans used in cooperation may beimplemented without diverging from the disclosed embodiment, and linkingfixtures together along one cooling system is also feasible, similar tocurrent ‘daisy chaining’ configurations.

The foregoing detailed description has been presented for purposes ofillustration. To improve understanding while increasing clarity indisclosure, not all of the electrical power connection or mechanicalcomponents of the air cooled horticulture light fixture were included,and the invention is presented with components and elements mostnecessary to the understanding of the inventive apparatus. Theintentionally omitted components or elements may assume any number ofknown forms from which one of normal skill in the art having knowledgeof the information disclosed herein will readily realize. It isunderstood that certain forms of the invention have been illustrated anddescribed, but the invention is not limited thereto excepting thelimitations included in the following claims and allowable functionalequivalents thereof.

I claim:
 1. An air cooled double ended high pressure sodium (HPS) lamp fixture 1 for growing plants in confined indoor growing spaces, comprising: a housing 200 having an open bottom 205 circumscribed by a housing edge 210, a first duct 235 being substantially aligned to a second duct 245, and a housing interior 220; a reflector 100 captured within the housing interior 220, the reflector 100 having a first aperture 105A located in opposition to a second aperture 105B, a reflector interior side 101, a reflector exterior side 102, a reflector top 104, and an open bottom 106 circumscribed by a reflector lip 103, the reflector lip 103 located adjacent to the housing edge 210 defining at least one cooling chamber 300 in the space between the reflector exterior side 102 and the housing interior 220, the cooling chamber 300 being in air communication with the first duct 235 and the second duct 245; a first socket 230A disposed to sealingly fill the first aperture 105A, a second socket 230B disposed to sealingly fill the second aperture 105B, the first socket 230A and second socket 230B constructed and arranged to cooperatively receive the ends of the double ended HPS lamp 2 as located within the reflector interior side 101; a cooling air stream 310 disposed through the cooling chamber 300 between the first duct 235 and the second duct 245; a glass sheet 30 and gasket 31 disposed at least proximate to the reflector lip 103 to seal the reflector interior side 101 from the confined growing space; at least one flow disruptor 160 disposed within the cooling air stream 310, the flow disruptor 160 being constructed and arranged to disturb laminar flow of the cooling air stream 310 creating local turbulence within the cooling chamber 300 whereby enhancing convective heat transfer from the reflector 100 into the cooling air stream
 310. 2. An air cooled double ended high pressure sodium (HPS) lamp fixture 1 for growing plants in confined indoor growing spaces, comprising: a housing 200 having an open bottom 205 circumscribed by a housing edge 210, a first duct 235 being substantially aligned to a second duct 245, and a housing interior 220; a reflector 100 captured within the housing interior 220, the reflector 100 having a first aperture 105A located in opposition to a second aperture 105B, a reflector interior side 101, a reflector exterior side 102, a reflector top 104, and an open bottom 106 circumscribed by a reflector lip 103, the reflector lip 103 located adjacent to the housing edge 210 defining at least one cooling chamber 300 in the space between the reflector exterior side 102 and the housing interior 220, the cooling chamber 300 being in air communication with the first duct 235 and the second duct 245; a first socket 230A disposed to fill the first aperture 105A, a second socket 230B disposed to fill the second aperture 105B, the first socket 230A and second socket 230B constructed and arranged to cooperatively receive the ends of the double ended HPS lamp 2 as located within the reflector interior side 101; a cooling air stream 310 disposed through the cooling chamber 300 flowing from the first duct 235 to the second duct 245; a glass sheet 30 and gasket 31 disposed at least proximate to the reflector lip 103 to seal the reflector interior side 101 from the confined growing space; at least one flow disruptor 160 enclosing the first socket 230A and first aperture 105A, the flow disruptor 160 being constructed and arranged to deflect the cooling air stream 310 from passing through the first aperture 105A creating local turbulence within the cooling chamber 300 whereby enhancing convective heat transfer from the reflector 100 into the cooling air stream
 310. 3. An air cooled horticulture fixture for growing plants in confined indoor spaces according to claim 1 or 2, wherein the flow disruptor 160 includes at least one flow turbulator 161, the flow turbulator 161 being operable to receive a portion of the cooling air stream 310 and eject the same in turbulent flow.
 4. An air cooled horticulture fixture for growing plants in confined indoor spaces according to claim 1 or 2, further comprising a sealing element arranged to stop moving air from passing around a socket 230 through an aperture 105 into the reflector interior side
 101. 5. An air cooled horticulture fixture for growing plants in confined indoor spaces according to claim 1 or 2, wherein the reflector lip 103 is located adjacent to and in substantial contact with the housing edge 210 such that heat is conductively transferred from the reflector lip 103 to the housing edge 210 thereby reducing gasket 31 temperatures.
 6. An air cooled horticulture fixture for growing plants in confined indoor spaces according to claim 1 or 2, wherein a gasket 31 located in the shadow of the reflector lip 103 compressively deforms between the glass sheet 30 and the housing edge 210 such that the gasket 31 makes a first air tight seal between the housing edge 210 and the glass sheet 30, and a second air tight seal between to the reflector lower lip 103 and the glass sheet 30, thereby making two air tight seals between the growing environment and the reflector interior side
 101. 7. An air cooled horticulture fixture for growing plants in confined indoor spaces according to claim 1 or 2, wherein a gasket 31 located in the shadow of the reflector lip 103 compressively deforms between the glass sheet 30 and the housing edge 210 such that the gasket 31 makes an air tight seal between the housing edge 210 and the reflector lower lip 103, thereby creating an air tight seal between the reflector interior side 101 and the cooling chamber
 300. 8. An air cooled horticulture fixture for growing plants in confined indoor spaces according to claim 1 or 2, wherein the cooling air chamber 300 has a minimum air gap 104A over the double ended HPS lamp of at least ⅜ of an inch. 